This circuit, found in a 1964 US documentation, consists of a selective amplifier that lets only 10 Hz pass around a 400 Hz center frequency with the indicated components.
This traditional amplifier configuration is from the National Semiconductor's Linear Applications Handbook...
We found this circuit in a Radio Electronics from February 1966. The circuit uses a germanium...
This circuit originally appeared in a publication of 1997. With the changes, the circuit can be...